Fort Pueblo started as a trading post in 1840. Not being on the main portion of the Santa Fe Trail, but the old Mexican Sangre de Cristo Trail, it suffered from a lack
of regular commerce. The Sangre de Cristo Pass had long been used as a more northerly route to Santa Fe. This is close to the route Pike followed. John C.
Fremont, a young civil engineer, was traveling in this area in 1836. On his first expedition he hired a scout who had been hunting for meat at Bent's Fort, Christopher
“Kit” Carson. On his second expedition in 1843, Fremont spent several days near the Pike's Peak region.
The southwestern border had been the subject of disputes between the U.S. and Mexico that dated back to the Louisiana Purchase explorations. Up to this time the
Mexican government was preoccupied with internal problems. There was now an ever increasing number from the US moving into the area. In Texas things were
starting to change. Friction was heating up relations between the Mexican government and U.S. settlers. In San Antonio, the Alamo turned into a battlefield in 1843.
The war between Texas and Mexico was spread north by traveling Texans. The United States was drawn into the problem when the Texans and some of the
Mexicans carried the conflict further north.
Trade on the Santa Fe trail stopped as travelers feared for their lives. President Polk ordered a force, called the "Army of the West," led by Stephen Kearny, into the
area in 1846. A goal of the invasion of Mexico was to secure the trail and Santa Fe. There were expectations that the Mexicans would be holding their ground at
Apache Canyon. Kearny marched on to Santa Fe, capturing New Mexico without firing a hostile shot. He left, traveling along the Rio Grande in September 1846. As
a result of the war with Mexico, the U.S. added the territory known as California, Arizona, Nevada, Utah and parts of New Mexico, Colorado and Wyoming.
The Santa Fe trail became a well defined route of commerce. Regular stagecoach and mail service connected Santa Fe and the East. The war with Mexico ended at
the right time. In 1849, stories of riches were drawing thousands toward Sutter's Mill and California gold. Today I-25 follows parts of the trail, and Colorado has part
of the land gained in the war with Mexico west of the Arkansas River.